The present invention relates generally to an electric switch and more specifically relates to an electric gas switch having a switching chamber divided into portions.
Swiss Pat. No. 574,673 issued to Stanislaus Ruffieux and Ekkehard Schade on May 15, 1976 discloses and electric gas-switch where the arc provides an internal pressure generation. Furthermore, the switch includes a device to influence the arc magnetically in order to improve the circuit-breaking capacity and to simplify the construction of the switch. In this way, the manufacture of the switch is made more economical. The switch utilizes a central pin which is made at least partially of a material such as graphite. The arc which is produced at the time of cut-off by the switch is divided by the central pin into both a rotating hot arc and an arc which in the course of the cut-off process is lengthening and also cooled by the quenching flow. In this way, the circuit-breaking capacity of the switch is intended to be improved.
In order to insure a subdivision of the arc, the central pin must have a sufficient length. Accordingly, a correspondingly large travel by the movable switch part is required. Furthermore, it is necessary in an arrangement utilizing an electrically conductive and insulated arranged central pin to consider that no specifically defined intermediate potentials exist when commutating the arc from the stationary switch part to the annular intermediate electrode. In addition an annular insulative part is placed between the stationary switch part, designed in tulip-shape, and the annular intermediate electrode. The annular insulative part could possibly influence the commutation discussed above.
It is the aim of the invention to further simplify the switch construction of electrical gasswitches of the above type, or to reduce, by eliminating at least one switch part being in contact with the arc, the areas of the switch which are subjected to a direct influence by the arc, and to simultaneously improve the arc commutation.
The invention overcomes the problems in the prior art by having the central pin made from an electrically insulating material. A comparison between the arrangement of the present invention and a switch such as is disclosed by Swiss Pat. No. 574,673 shows that the central pin, used by the latter, consists of an electrically conductive material and is fastened by way of an insulative part to the terminal flange. However, in the case of the gas-switch of the present invention, the central pin which is made of an electrically conducting material is omitted or alternatively replaced respectively by an insulative pin.
It will be particularly advantageous if the central pin is designed in such manner that it will taper at its free end. The primary advantage of the invention is to improve a heating of the gas filling the switch to result in a more economic operation of the gas-switch. The switch is not only of a simpler construction than the known comparable systems but can also be made smaller in size than can the known arrangements. Additional advantages are mentioned below in connection with the explanation of the invention.